Associate Professor Eugene Tan of the Singapore Management University said it is within the Government's power to ask Facebook for information it believes is relevant for criminal investigations under the Criminal Procedure Code.

As for "non-criminal type requests", they could relate to "matters such as national security, intellectual property rights infringement (which could be criminal and non-criminal), or terrorism activity," he added.

Facebook checks each request for legal sufficiency and requires officials to provide a description of the legal and factual basis for their request.

"We push back when we find legal deficiencies or overly broad or vague demands for information," it said.

The Government also made eight requests to preserve 15 user accounts. This essentially centres on preserving them in connection with official criminal investigations for 90 days.

Globally, governments made more than 78,000 requests in the first half of this year, on more than 116,000 user accounts. This is a 21 per cent increase compared with the second half of 2016.

The US tops the list for government requests, with 32,716 requests on 52,280 user accounts. The second country on the list is India, with 9,853 requests on 13,752 accounts.

Singapore ranks 26th on the list of 129 countries.

Facebook's policy is to notify users when such requests are made, unless legally prohibited or in "exceptional circumstances" like child exploitation cases, emergencies or when notice would be counterproductive.